Unwanted circles

[noah@noahsart.co.nz]

Hi.
I have a large project to cut parts for a boat mould from MDF.
I have been sent 50 drawings done in Autocad, saved as DXF, which I still need to outline in Vector and then convert to shopbot.
The trouble is, some points on the line, apparently randomly, end up as little circles on the path, which the machine then follows reliably.
Nothing is apparent on the DXF paths at all, they can only be seen on the shopbot preview when zoomed in. The circles are about a quarter of an inch in radius, (true path) I might get about 7 circles in a row on a curved path, they do occur when there are lots of points, not on a straight segment.
Help!

[gbatten]

Simon,

Email me a couple of the DXF drawings and I'll take a look.

Gene Batten
BattenProducts@charter.net (mailto:BattenProducts@charter.net)

[stickman]

Simon,

Why are you saving as a dxf and then outline in vector? Do you have part wizard? Can't you go direct from dxf into shopbot. I use part wizard, I guess that is why I ask.

Anyhow, what I think you are getting is little loop lines within the dxf drawing at line points. If you zoom in on those points in AutoCAD or another drawing program you will probably find a small, really small line segment. I would guess this is what is creating your loops.

Just my thoughts this morn...

[artisan]

Generally speaking, it's a toolpath issue. The little (usually red) circles, are indicators that your vectors are crossing back over themselves. Magnify your drawings and edit, move or delete some of your points. When the circles are all gone, your toolpaths will be clean.

It can be caused by a single point causing the router to touch or cross a previously machined vector in your toolpath....D

[noah@noahsart.co.nz]

Thanks for all your help. It looks like I am not alone in this loopy problem.
It is now a new day in New Zealand, so I will try the decimal zero suggestion this morning on stuff that I know has generated circles.
Jay, Somehow I have never seriously tried Parts Wizard. I find it slightly opaque. However in this case all the 8by4 sheets have been laid up in a single sheet, so it has to be divided up before importing anyway...

[noah@noahsart.co.nz]

Well I have tried changing the decimal zeroes, and the circles turn into pull-ups...(?) in the same places as there were circles before.
I still cannot find anything unusual about these positions in Vector. But at least pull ups are not so destructive so I guess I can live with them until the problem is sorted out..

[srwtlc]

Simon,

If you are using Vector to generate your code (.sbp) , be sure that you are using the right NC post processor file (shopbt2g.cfg). And at the same time be sure that you have Vector NC (the code window) set to 6 dialogdigits under Options/Units.
shopbt2g.cfg

3824 (10.3 k)

Also, if you can select one entity of your drawing, then Ctrl-W, and if it walks all the way back around to the start point, then your path should be closed just fine (no overlaps or breaks).

Scott

[ron brown]

Simon,

You may not have the latest version of Vector. Vector 8 and 9 (pre 9.6) have a "Loop delete" program available.

Check the IMSRV forum.

Ron

[noah@noahsart.co.nz]

Ron I have Vector 9. Where do I find loop delete?
Scott I have shopbt2f in vector. I cannot activate the download shopbt2g.cfg from your attachment, comes out as garbled text on my outlook express.

[srwtlc]

Simon, you have mail.

Scott

[ron brown]

A lot of Vector information can be found in the Vector forums. Here is a link to the discussion of "loops": http://www.imsrv.com/discus/messages/12/99.html

The Vector forum is not as active as the forum here. Many Vector questions are answered there as ShopBot has shipped with PartWizzurd for a few years now.

Ron